Apple Integer BASIC tokenized file

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File Format
Name Apple Integer BASIC tokenized file
Ontology
Released 1976

Apple Integer BASIC, created by Apple co-founder Steve Wozniak, was first created as Apple I BASIC, for the Apple I hobbyist computer which was the first product of the newly-founded Apple company. On the Apple I, it had to be loaded from tape. When the Apple II came along the following year, it had a slightly improved version of this BASIC built into its ROM, called "Apple Integer BASIC" because it supported only integer numbers. Not long afterward, Applesoft Floating Point BASIC was licensed from Microsoft and made available to be loaded from tape or disk. Subsequent Apple models starting with the Apple II+ had Applesoft BASIC in ROM, so Integer BASIC went out of use.

Integer BASIC programs were stored in a tokenized format, in files which were designated in Apple DOS directories as type "I".

Unlike most other BASIC tokenizations which preserve literal printable ASCII characters in the 7-bit range and use high-bit (#128-#255) characters for tokens and other special functions (sometimes also using some of the ASCII control characters in #0-#31 for special functions as well), Integer BASIC tokenization instead stored normal ASCII characters with the high bit set, so that a letter A (ASCII 41 hex) was stored as C1 hex. Then the 7-bit characters with the high bit clear were used for tokens. Also, some of the control characters in the high-bit range (B0 - B9 hex) were used as flags to signal that the next two bytes were an integer constant (little-endian), except when the B0-B9 byte was preceded by an alphanumeric character (with high bit set), in which case it was considered part of a variable name.

Program lines were separated with the byte 01. The null byte 00 was not used; this is something which might be noted as a way to distinguish Integer BASIC programs from S-C Assembler source files, also stored with file type "I", but which used nulls as line separators. (But note that both bytes 00 and 01 might appear as part of integer constants.)

All BASIC keywords were assigned tokens, including command keywords which were only allowed in immediate mode on command lines, and couldn't actually appear in stored programs. Some keywords and symbols have multiple tokens for them, sometimes a large number of them; this appears to distinguish different contexts and meanings of the symbol for the assistance of the interpreter, but there doesn't seem to be any clear documentation of all of these distinctions. Some of them distinguish unary (one-argument) and binary (two-argument) versions of mathematical functions.

The program file started with a two-byte little-endian integer giving the file length, and each line started with a one-byte line length (thus, lines could not exceed 255 tokenized bytes) and a two-byte little-endian integer for the line number.

Contents

Tokens

Blank values indicate either that the token is unused or is used for something unknown.

Hex Dec Token meaning
00 0 HIMEM: (direct cmd)
01 1
02 2 _
03 3 :
04 4 LOAD
05 5 SAVE
06 6 CON
07 7 RUN
08 8 RUN
09 9 DEL
0A 10 ,
0B 11 NEW
0C 12 CLR
0D 13 AUTO
0E 14 ,
0F 15 MAN
10 16 HIMEM: (binary)
11 17 LOMEM: (binary)
12 18 + (binary)
13 19 - (binary)
14 20 * (binary)
15 21 / (binary)
16 22 = (binary)
17 23 # (binary)
18 24 >=
19 25 >
1A 26 <=
1B 27 <>
1C 28 <
1D 29 AND
1E 30 OR
1F 31 MOD
20 32 ^
21 33 +
22 34 (
23 35 ,
24 36 THEN
25 37 THEN
26 38 ,
27 39 ,
28 40 \
29 41 \
2A 42 (
2B 43 !
2C 44 !
2D 45 (
2E 46 PEEK
2F 47 RND
30 48 SGN
31 49 ABS
32 50 PDL
33 51 RNDX
34 52 (
35 53 + (unary)
36 54 - (unary)
37 55 NOT
38 56 (
39 57 = (unary)
3A 58 # (unary)
3B 59 LEN(
3C 60 ASC(
3D 61 SCRN(
3E 62 ,
3F 63 (
40 64 $
41 65 $
42 66 (
43 67 ,
44 68 ,
45 69 ;
46 70 ;
47 71 ;
48 72 ,
49 73 ,
4A 74 ,
4B 75 TEXT
4C 76 GR
4D 77 CALL
4E 78 DIM
4F 79 DIM
50 80 TAB
51 81 END
52 82 INPUT
53 83 INPUT
54 84 INPUT
55 85 FOR
56 86 =
57 87 TO
58 88 STEP
59 89 NEXT
5A 90 ,
5B 91 RETURN
5C 92 GOSUB
5D 93 REM
5E 94 LET
5F 95 GOTO
60 96 IF
61 97 PRINT
62 98 PRINT
63 99 PRINT
64 100 POKE
65 101 ,
66 102 COLOR=
67 103 PLOT
68 104 ,
69 105 HLIN
6A 106 ,
6B 107 AT
6C 108 VLIN
6D 109 ,
6E 110 AT
6F 111 VTAB
70 112 =
71 113 =
72 114 )
73 115 )
74 116 LIST
75 117 ,
76 118 LIST
77 119 POP
78 120 NODSP
79 121 DSP
7A 122 NOTRACE
7B 123 DSP
7C 124 DSP
7D 125 TRACE
7E 126 PR#
7F 127 IN#

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